Liver enzymes refer to a group of proteins produced by the liver that aid in various metabolic processes within the body. These enzymes are essential for breaking down and converting nutrients into energy, as well as detoxifying chemicals and drugs from the bloodstream. Some common liver enzymes include alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT) and alkaline phosphatase (AP). Abnormal levels of these enzymes in the blood can indicate liver damage or disease.